Conventional motor-driven apparatus such as motor-driven chain saws have as standard equipment a lubricating-oil pump feeding lubricating oil from an oil tank to the moving saw chain.
Known motor-driven apparatus such as motor-driven chain saws where the saw chain moves around a guide bar are equipped with a lubricating-oil pump which in the operation of the chain saw continuously feeds lubricating oil for the chain links into a groove in the guide bar. Motor driven apparatus of this type are also equipped with other attachments or tools, for example with hedge trimmers, drills or the like which require no lubrication during operation. Further, it is known to equip motor-driven chain saws with sharpening devices which permit resharpening the cutting links with the motor running and the saw chain rotating.
When working with the known attachment tools which require no oil lubrication, it has been customary to drain the oil tank prior to mounting the attachment in order to avoid an unintentional oil leakage. For this purpose, the lubricating oil was collected in a suitable container to be saved for later use. In various applications the operator did not drain the oil tank so that oil continued to be fed without being needed; this resulted in additional oil consumption and environmental pollution. Also in other operations such as when the tool is being operated in the idle state, continuous lubrication of the tool is unnecessary.
In U.S. Pat. No. 2,070,203 there is disclosed a reciprocating oil pump in which the amount of oil pumped can be varied between a maximum delivery and a minimum deliver. As disclosed the piston in the pumping cylinder is provided with a pair of spaced cams rotatable with the piston. A sleeve providing a bearing for a portion of the piston is provided and has a cam pin secured to it for reciprocating the piston. The sleeve bearing is rotatably adjustable so as to change the relative circumferential position of the cam pin and cam surfaces to thereby change the quantity of oil pumped from a maximum delivery to a minimum delivery.
In U.S. Pat. No. 4,678,411 there is shown a control wherein the volume of oil is regulated by the interaction of a control cam and a control bolt which may be rotated to vary the stroke of the pump.
The U.S. Pat. No. 2,347,364 discloses the use of tapered pin and a matching two-walled cam surface to reciprocate a rotating piston.
In U.S. Pat. No. 4,797,073 a tapered pin cam follower is used to vary the stroke of a piston.
U.S. Pat. No. 4,636,147 discloses a lubricating-oil pump for a motor-driven apparatus which provides for activating and interrupting the supply of lubricating oil to the tool driven be the motor.
Accordingly, a principal desirable object of the invention is to provide a lubricating-oil pump system having a rotating and reciprocating piston for a motor-drive apparatus and the like with a state of art control apparatus for regulating the quantity of oil from full maximum flow through a full intermediate range to a no flow or interrupted flow state.
Another object of the invention is to provide such control of flow by means of a camming pin having a cam follower and a complementary cam surface where the stroke of the pump's piston is inversely proportional to the predetermined axial space between the cam follower on the camming pin and the cam surface; the space controls the percentage of time the cam surface and cam follower are in contact during a revolution of the piston.
Yet another object of the invention is to adjust the piston stroke of a lubricating-oil pump having a rotating and reciprocating piston by varying the time per revolution a cam surface is on the piston in contact with its complementary cam follower and control pin.
Still another object of the invention is to provide a lubricating-oil pump having a rotating and reciprocating piston where the volume of oil pumped is a function of an axial adjustment of the piston and the time per revolution a cam surface is in contact with its cam follower.